This is the central website for available
housing for sale in the Netherlands, and some boats will be listed
there as well, if they are handled by a licensed real estate agent [makalaar].

If the direct link doesn't work right, go to
www.funda.nl, uitgebreid zoeken. select the Plaats [Noord Holland],
city[s] you want, then the right arrow to move them to the search
area. then under "soort woning", select "woonboot"